Merge pull request #1 from deshipu/master

Define the models
fix: ... before first installation ralph_pricing ... :)
level up ralph version
Merge pull request #2 from wmatyskiewicz/setup

Fix: setup
remove ForeignKeys in models, added ralph_assets to install_requires in setup.py, added init migration
change field name
Merge pull request #3 from wmatyskiewicz/models

models
Add handling for sync plugins